CHAPTER XX. 
THE HEMORRHAGIC SEPTICEMIA GROUP. -TULAREMIA. 
The Hemorrhagic Septicemia or Pasteurella Group of bacilli com- 
prises a number of organisms which possess in common peculiarities 
of morphology, similarity of cultural characters and great pathogen- 
icity for animals. 
Morphologically they are short, ovoid bacilli of relatively large 
diameter, measuring about 0.5 to 0,8 micron in the widest part, and 
varying in length from 0.8 to 1.5 microns. The organisms usually 
exhibit marked pleomorphism in old lesions and in old cultures. 
They are non-motile, uniformly Gram-negative, and exhibit a marked 
tendency toward bipolar staining; the stainable substance is collected at 
the ends of the bacillus, separated by a central, faintly stainable area. 
The hemorrhagic septicemia bacilli grow well upon ordinary cul- 
tural media, and they are chemically relatively inert. Indol is pro- 
duced by certain types, but not by all. Gelatin is not liquefied. Acid, 
but no gas, is formed in glucose, lactose and many hexoses. The 
fermentation of other sugars and starches has not been thoroughly 
studied. 
The type of infection induced is usually an acute generalized septi- 
cemia, which, because of punctate hemorrhages on serous surfaces, 
and in the internal organs, is called hemorrhagic septicemia. Inflam- 
mation of the intestinal tract, and frequently the respiratory tract, is 
usually an important feature of the infection. 
The most important animal diseases are chicken cholera, swine 
plague, rabbit septicemia, and a similar disease of cattle and wild 
herbivora. Plague is the disease of man which most closely approaches 
hemorrhagic septicemia of the lower animals. 
The lesions caused by B. pestis in experimental animals and in the 
naturally occurring disease in rodents present many similarities to the 
hemorrhagic septicemias, and occasionally a distinction must be made 
between the plague bacillus and other members of the group. The 
Indian Plague Commission state that B. pestis may be differentiated 
from the other members of the group by its ability to develop and 
produce acid (but no gas) in glucose and mannitol media containing 
bile salts, particularly sodium taurocholate; they claim that the other 
organisms of this group will not grow in this medium. 
Bacillus Pestis.— Plague, the most dreaded of the acute epidemic 
diseases, has at somewhat irregular intervals swept over parts of the 
Orient, and during the earlier centuries of the Christian era, even 
